I have created a module which creates a GML file to show the network of the dataset. Now I noticed the visualisation button but unfortunately GML is not (properly) supported. Using the more info button I arrived at this page:

No - GML is not supported as a) GML isn't a datatype included with Galaxy, and b) GraphVis (and more specifically cytoscapejs) would need to know how to parse it. I haven't been able to find anything on cytoscapejs supporting GML yet - let me know if you find it as that would make things easier.

It should work on a plain installation - it's not very exciting though.

The plan going forward is to re-incorporate at least XGMML and SIF datatypes (which are shipped with Galaxy). If you'd want to add the GML datatype and a parser/dataprovider for it - please, let us know - that would be great.